Various types of petroleum oils are added to the rubber formulations in order to reduce viscosity, improve processing properties, increase low temperature flexibilities and decrease cost. However, polycyclic aromatic hydrocarbons (PAH), which are the main constituent of aromatic oils for rubber formulations, are highly carcinogenic. Therefore, there are benefits from the use of safe oils such as seed oils instead.
Soybean oil could be an excellent resource to replace petroleum oils in various fields. Efforts of replacing the conventional petroleum oils with soybean oil were made by many researchers. Soybean oil can be hydrogenated and used in food industries, or can be epoxidized and used in PVC and coatings. Soybean oil can also be used to produce bio-fuel, polyols and polyurethanes. In rubber industry, soybean oil can be added directly or be vulcanized and used as a plasticizer in the rubber matrix.
Soybean oil can be used as a replacement of conventional petroleum plasticizer. However, it is still necessary to further advance the usage of soybean oil in the rubber formulations to obtain improved properties over similar formulations using petroleum oils.